HK1001301A1 - Apparatus and method for comprehensive copy protection for video platforms and unprotected source material - Google Patents

Abstract

A video recording platform prevents both analog and digital copying of copy protected material. The platform may input and output both analog and digital video signals. At said analog input, a detector detects conventional copy protection in the analog input video, and in response disables recording thereof. At the digital input, a first detector detects a copyright signature present in the input material and in response prevents recording. A specially adapted video recorder, playback device or set top decoder copy protects video source material which has a copyright signature. A copyright signature is provided in a predetermined location in said video signal to be protected. The video recorder, playback device, or set top decoder upon detection of the copyright signature on its input or at playback, modifies the output standard (NTSC) video signal with a conventional copy protection process and the digital output with a new copyright signature. The input digital signal may contain a scrambling of the digital video signal in addition to the copy protection signature. In addition, an authenticating signature may be added to the digital video signal and detected as part of the copy protection process. As part of the copy protection, a television receiver includes a copy protection and descrambling system.

Description

Video platform and method and apparatus for integrated copy protection of unprotected source material

Ryan, assigned serial number 08/287800, filed on 9/8 of 1994 and assigned with the present invention.

The present invention is directed to a method and apparatus for copy protection and scrambling for use with various video platforms, including, but not limited to: (1) digital video recorders in which copy protection of analog and digital video signals associated with digital recording or playback devices is desired; (2) see pay-once-ppv (pay Per view) digital decoder, wherein copy protection of digital video signals received by the decoder is desired; (3) digital video disc players in which copy protection of digital video signals associated with a digital video disc recorder is desired. In addition, the copy protected and scrambled portions may be used for any video material whose original source material is not copy protected.

The continued improvements in recording heads, processes, high speed digital signal processing, and tape formulations now make the production of consumer digital Video Cassette Recorders (VCRs) feasible. A consortium of manufacturers has been called specifically together to promulgate the technical standards for consumer digital VCRs. Similarly, similar efforts are underway for the new MPEG-2 digital video disc standard-DVD.

The success of a digital VCR as a consumer product will be critically influenced by the decision of the film and other varieties of programs that the film software provider releases to support the digital VCR. The potentially extremely high image quality of digital VCRs and their ability to be reproduced without limit is a serious psychological barrier for many program providers, particularly the hollywood studio. As digital VCRs enter the hands of professional and amateur pirates, they will be seen as a major threat to financial revenue.

To encourage program providers to view digital VCRs as an opportunity rather than a threat, there is a need for sophisticated copyright protection systems that provide high security for certain copyrighted video programs. The implementation of such a system requires that the consumer's ability to view the proper pre-recorded program at any time using a digital VCR is not compromised in any way.

Various video copy prevention systems that have been implemented or proposed to date attempt to prevent a VCR from making a usable copy of some pre-recorded or transmitted video program in one way or another. These systems fall into two categories-referred to as unidirectional and bidirectional recording prevention systems, respectively.

One-way copy prevention systems are designed to cope with a large number of existing VCRs and televisions, as described in the following patents: U.S. Pat. No.4,631,603 issued to John O. Ryan on 23.12.1986 and assigned to Macrovision; U.S. Pat. No.4,914,694, issued to Leonard at 3.4.1990 and assigned to Eidak Corp; and U.S. patent No.4,577,216, issued to John o. ryan and assigned to Macrovision on 3/18 1986. Designers of one-way systems must identify and exploit fundamental differences from existing VCR and tv sets in the way video signals are used. Since existing VCRs are designed to record all video signals of a current standard (e.g., NTSC or PAL), the unidirectional anti-recording system must generate non-standard video signals. This requires that these non-standard copy protected video signals be playable on all existing VCRs and televisions, severely limiting the design of one-way systems and making it difficult to achieve greater than 80% effectiveness.

Various well-known video signal copy prevention schemes, including U.S. patent No.4,631,603(John o. ryan, dec.23, 1986, assigned to Macrovision), which is incorporated by reference, are directed to modifying an analog video signal to inhibit it from acceptable video recording. This patent adds a number of pulse pairs to each of the unwanted lines of the vertical blanking interval of the video signal, each pulse pair being a negative going pulse followed by a positive going pulse. The effect is to scramble the Automatic Gain Control (AGC) circuit of a VCR recording such signals so that the recorded signals are generally of poor quality and cannot be viewed.

Another approach to copy protection of analog video signals is disclosed in U.S. patent No.4,914,694 (issued to Leonard on 3.4.1990 and assigned to Eidak Corp, incorporated by reference). The Eidak system (see summary) increases or decreases the length of each video field from a standard length, either keeps the standard number of lines per frame constant and changes the time interval of the horizontal lines in each field, or keeps the standard time interval of each line constant and changes the number of horizontal lines making up each frame.

These video protection systems modify the video signal to be recorded (e.g., on a magnetic tape) or to be broadcast (e.g., PPV television programs) so that it is difficult or impossible to reproduce by a normal VCR. When a video tape recorded with a copy-protected video signal is played back and viewed by a VCR, the copy protection process is substantially transparent, i.e., it does not interfere with viewing. However, any attempt to copy the video signal of a magnetic tape by recording the output of a first (playback) VCR with a second VCR will result in a somewhat degraded image depending on the different efficiencies of the particular copy prevention system. These existing video copy prevention systems protect only analog video signals that are broadcast and recorded using current consumer video technology.

On the other hand, bi-directional copy protection systems require special detection circuitry to be included in substantially all standard VCRs. Therefore, the only condition for bidirectional systems to be a viable alternative to unidirectional systems is to introduce new systems to implement them. The detection circuit searches the protected pre-recorded or transmitted video signal for a special copy-never signal embedded therein and, if found, causes the VCR to stop recording. A bi-directional copy protection system can be designed to be substantially 100% efficient. For this reason, copyright owners prefer bi-directional systems over unidirectional systems.

However, in order for a bi-directional system to be of maximum value, it must be designed as an integral part of the new VCR model, and the special detection circuit must be included in all manufactured VCRs. This may have legal and contractual difficulties in ensuring the cooperation of all VCR manufacturers. If the VCR is produced illegally, the VCR can be bought by a video shop owner or a professional pirate and used for illegally copying the protected program for sale or lease. This necessity to ensure 100% VCR vendor cooperation is a weakness of the two-way copy protection systems proposed to date.

It is widely believed that consumer digital video tape recorders will soon come on the market. To remain compatible with analog broadcast video signals and analog video tape recorders, it is likely that at least the first generation consumer digital video tape recorders will be digital and analog "hybrid" systems. Such a system would have the ability of current analog VCRs to record analog input signals and provide analog output signals during playback, and would also have corresponding digital recording and playback capabilities. Thus, these new hybrid digital video tape recorders internally convert the incoming analog signal to a digital signal and record the digital signal on the tape as a digital data stream. During playback, the digital data stream on the tape can either be displayed as a digital signal on a digital television set (not currently available) or converted back into a conventional analog video signal (e.g., an NTSC signal used in the united states) in a hybrid video recorder. This ability to convert received analog signals into digital data streams within the system is important because there is currently no source of digital video programming (tape or broadcast) available to the consumer.

Such a hybrid video recorder will likely employ a "consumer" digital recording standard that is different from the current professional digital system standard. Such a consumer digital video format has not yet been established. Such digital video recorders may include a conventional "front-end" rf tuner, and also an rf modulator on the output side, as is the case with current conventional analog VCRs (where analog video refers to NTSC, PAL, SECAM or Y/C signals). The digital recording standard for consumers may be basically a data structure representing the video signal as a (binary) data bit stream and suitable error concealment coding and physical standard for magnetic tape.

Professional digital video tape recorders are also known, although due to their high price, such digital video tape recorders (both recording and playback are digital) are only available on the professional market today. Such digital systems trade considerable bandwidth for distortion-free performance, i.e. essentially one video frame has to record more information. The advantage to the user of a digital video recorder is that each generation of copies does not significantly degrade the image quality as long as the signal is recorded and played back in the digital domain. This is different from the case of conventional and analog video recording techniques. Current digital video recorders (not consumer use) employ so-called "D-1", "D-2" or "D-3" video recording standards and require special video tapes.

Since digital video tape recorders can reproduce with high fidelity, which in turn will stimulate reproduction, it is important that such consumer video recorders are designed to inhibit or prevent unauthorized recording. For example, illegal copying of copyrighted video material using a video recorder must be prevented, and playback of such illegally copied material should also be prevented. Current analog video copy protection techniques are not available in the digital domain. There is therefore a need for a new copy prevention system suitable for use in such mixed digital and analog video tape recorders in which the material recorded on the tape is a digital data stream. A typical situation that needs to be prevented is to use a hybrid video tape recorder to copy the output signal from a conventional VHS VCR, with conventional copy prevention measures being added to the tape played back from the VHS VCR. The problem posed is to prevent new hybrid digital-analog video tape recorders from copying material from such tapes. Otherwise, the advent of such hybrid video recorders would stimulate copyright infringement.

Some of the problems listed above have been addressed by U.S. patent 5,315,448 (issued to Ryan at 24.3.1994 and assigned to Macrovision corp., incorporated by reference).

Digital VCRs pose a potential threat to video copyright owners in three ways:

1. it has the ability to make high quality copies of existing analog video programs (NTSC or PAL), whether from pre-recorded tape cassettes, compact disks, or cable PPV decoders.

2. It has the ability to make perfect copies of prerecorded digital cassette tapes, or perfect copies of digital video programs from future DVD players, or perfect copies of digital programs from PPV decoders with digital video output.

3. It has the ability to give analog video output from pre-recorded digital cassette tapes that is close to studio quality, so that it can be reproduced with existing VHS and 8 mm VCRs. The quality of these simulated replicas is comparable to current master VHS publications.

A digital recording video platform provides copy protection in both the digital and analog domains. The copy protection includes scrambling and descrambling circuitry. For foreign analog video, the recorder detects the presence of copy protection and inhibits recording. For foreign digital video, each anti-copy bit is detected to inhibit recording. The scrambling process is performed in the digital part of the copy protection system. For the recorded material, anti-copy bits are detected in the digital playback video, which is modified by an analog video anti-copy measure after conversion to an analog signal. When the playback system detects the anti-copy bits, the descrambling circuit is activated. To protect the digital output of the video recorder, a new set of copy protected data and scrambling is added on the digital output device. A simplified descrambling device is included in the digital receiver.

Analog or digital source video material (either pre-recorded or from an external source) has a mark that prevents copying. A playback device (1) detects the mark and (2) prevents subsequent copying of the digital source data by a second digital video recorder, resulting in alteration of the played back standard video signal by an analog copy prevention process. This is suitable for playback devices where the source video cannot be copy protected but where a standard (NTSC or PAL) video signal is present that is recorded after playback.

The device and the method are mainly characterized in that:

1. all copy protected digital video signals contain a 1-bit dynamic Copyright Signature in the serial data stream and are also scrambled in the digital domain using the scrambling technique described in the pending application (serial No. 08/287800 filed by John o. ryan, 1994, 8/9). Although the details of this scrambling technique are described in the above-identified accepted application, it is not necessary to know this technique in detail for a complete understanding of the present invention. The 1-bit copyright flag also carries a part of descrambling information.

2. Two scrambling algorithms, we call a and B, are used. They all use the same scrambling principle as referred to above. All copy protected programs, whether distributed on digital cassette tape or future DVD or digital PPV formats or other platforms, are scrambled with the algorithm "A" at the start point. Only legitimate devices (devices using the methods and techniques of the present invention) -digital VCRs, DVD players or PPV decoders with digital output-contain an "a" descrambler that provides clear digital video for internal use and for conversion to analog NTSC or PAL for external existing television sets.

The purpose of "a" scrambling is to ensure that the copy protected digital video medium can only be played on legitimate hardware which always adds copy protection to the output signal for the copy protected program.

3. These legitimate machines also contain a "B" scrambler that scrambles the clean digital video again before it is applied to the corresponding digital video output ports of these machines. A new dynamic copyright flag bit is also added to provide the appropriate "B" descrambling information.

The purpose of the "B" scrambling is to ensure that the copyright signature (discussed more fully below) prevents a legitimate digital VCR from making a copy. The copyright notice cannot be removed by the "inside box" because, if this is done, the inside box would also remove part of the descrambling information carried by the copyright notice.

4. Future television sets with digital video inputs that comply with the disclosed signal will contain a "B" descrambler to provide clear images from the copy protected video source.

5. Programs that are only distributed on protected pre-recorded digital media also carry unique authentication indicia. The purpose of the authentication mark is to provide a means by which a legitimate VCR can determine whether the played back cassette is a duplicate of a protected program, in which case the playback signal will be interrupted or a "stop" mode of the machine will be initiated.

The working principle is as follows: an authentication system within a legitimate VCR looks for a copyright flag in the digital signal from the tape, and allows the tape cartridge to continue playing only if an authentication flag, if any, is also detected. Only the master protected digital cassette tape has authentication marks added at the time of manufacture. The feature of this mark is that it does not appear in the output signal of a VCR playback and therefore it does not transfer to any copy copied by the protected film tape. However, all copies of protected digital programs, whether copied from cassette tapes, video discs or PPV decoders, will still contain copyright indicia. The absence of authentication marks on these copies will then reveal their illegal nature and the authentication system in a legitimate VCR will not allow them to be played.

6. The digital VCR adopting the method also comprises the following subsystems:

a. a copyright token detector at the digital video input.

b. An anti-copy process detector at the analog video input that inhibits these VCRs from copying standard anti-copy programs.

A PPV anti-copy processing signal generator that prevents copying of the analog output when the copyright token is detected on the signal from the tape.

d. A logic system that causes the VCR to stop playing the cassette that contains the copyright notice without the authentication notice (indicating an illegal copy).

The purpose of the copy and scrambling prevention apparatus and method is to provide a firm protection against these threats for the copyright owners concerned, without at all limiting the legitimate use of a digital VCR.

Fig. 1 is a block diagram of a hybrid digital video recorder according to the present invention.

Fig. 2 is a block diagram of a digital video disc player according to the present invention.

Fig. 3 is a block diagram of a digital video PPV decoder according to the present invention.

Fig. 4 is a block diagram of a digital television set according to the present invention.

Fig. 1 is a simplified block diagram of a legitimate digital VCR illustrating how copy prevention and scrambling functions are implemented.

Each block contains conventional elements that are currently commercially available or can be readily fabricated by one of ordinary skill in the art in light of the following description. One possible exception is the recording and playback system 10, which is the main subsystem of such devices. The current professional digital video recorder contains the tape holder mechanism and the electronic device, but the professional digital video recorder is designed for recording and playing data under the current professional digital video standard. The recording and playback system 10 may be of the type that is encompassed by such current commercial professional systems. However, since the hybrid system shown in fig. 1 is anticipated to be primarily (but not exclusively) consumer-oriented, such a system may have different digital tape deck mechanisms and electronic devices, of the type suitable for low-cost mass production and designed in accordance with the consumer digital video format as yet unidentified.

In summary, the recorder of fig. 1 can be made with existing components, including professional digital tape holders, which are now commercially available from various companies. The type of tape played on the tape deck 10 is (1) video cassette or (2) disk-to-disk recording.

The video recorder of fig. 1 is a hybrid device that receives a conventional analog video signal at input port a. The "input" edge in fig. 1 also gives a digital video input port D that receives digital video from an external source. The port D receives a broadcast digital video signal to be commercially broadcast in the future or a broadcast digital video signal from another digital video recorder, a digital playback apparatus, or a cable box.

The analog video signal or component video signal 12, such as NTSC, PAL, is applied to an anti-copy process detector 26 to detect an anti-copy signal, such as the anti-copy signal of Macrovision Corporation described in the above-mentioned U.S. patents 4,631,603 and 4,577,216. If the analog input signal is copy protected, the detector 26 generates a logic signal to open the switch 16 to inhibit recording of the signal. If the analog input is not copy protected, the video signal passes to the analog to digital converter 18 and then to the input select switch 30. This detection circuit is described in U.S. patent 4,907,093 (John O. Ryan, 1990, 3, 6, and assigned to Macrovision Corporation, herein incorporated by reference).

Since the apparatus of fig. 1 records digital signals, the analog video signal at port 12 is converted to the desired digital format by analog to digital converter 18. Such analog-to-digital converters are well known in the video field, and the details of the construction of the analog-to-digital converter 18 are determined by the nature of the digital recording system to which the recording and reproducing system 10 is adapted.

The digital video data stream output by the analog to digital converter 18 is applied (via switch 30) to the recording and playback system 10. The person (or machine) operating the video recorder of fig. 1 decides whether he/she is recording an analog video input signal 12 or a digital video input signal 14 each time. The switch 30 (automatically or manually controlled) selects either signal 12 or 14 as the input signal received by the tape deck 10 to be recorded.

The digital video input signal 14 is applied to a copyright flag detector 20. if the digital video input signal is copy protected, the detector 20 generates a logic signal to open a switch 22 and disable recording of the digital video input signal 14. If the digital input is not copy protected, it is routed directly to the input select switch 30.

The output of switch 30 is applied to the digital VCR recording and playback system 10. The details of the rendering system are not relevant to the copy prevention system and will therefore not be described in detail.

The recorder of fig. 1 may be conventionally equipped with a radio frequency tuner (not shown) on the "input" side to extract the video (NTSC or PAL) signal from the radio frequency modulated video (television) signal. Similarly, a radio frequency modulator (not shown) may be provided on the "output side" to convert baseband or other video signals to radio frequency modulated video signals (television) for coupling to the antenna input of the television.

During playback, the demodulated and error corrected digital signal from the tape on line 31 is applied to the copyright mark detector 32. if the tape signal is copy protected, the detector 32 generates a logic high level 46. Note that detectors 20 and 32 are functionally identical, so in practice one unit can be used with appropriate switching.

The above-described authentication mark can be conveniently and easily implemented by frequency-modulating the recorded serial digital signal with a square wave having a frequency such that an integral multiple of a complete track is recorded in a half cycle thereof. The required frequency offset may be quite small, perhaps around 1 percent. Thus, for example, for one complete track, the recorded signal may be timed at a rate 1% above the average rate and for the next complete track the signal may be timed at a rate 1% below the average. This modulation can be easily extracted by a voltage controlled oscillator or discriminator that tracks the signal on the tape during playback.

The advantage of using frequency modulation to record integral multiples of a complete track per half cycle is that relatively small modulations can be easily detected in the presence of frequency modulated "noise" caused by unavoidable head-tape scan speeds and tape stretching, etc. This noise is mainly at the frequency of the track and its harmonics and can therefore be easily suppressed by sampling or filtering.

Since the signal on the tape is retimed with a stable clock as part of the normal demodulation process, this authentication mark is completely "lost" in the demodulation and error correction system of the machine and therefore does not appear in the digital video output of the VCR and is not transferred to any duplicate. However, as previously mentioned, it is easily detected to authenticate playback of the original copy-protected cartridge.

This out-of-band modulation of the digital video signal carries a third signal detector for the authentication mark applied to the decoder 38, the output of the decoder 38 being applied to the authentication mark detector 40. The authentication mark is always generated when a tape duplicator or an individual of a magnetic recording tape adds a copyright mark to a signal during the production of a master tape. The authentication detector 40 generates a control signal 42 of a logic high level when the authentication signal is detected.

The logic signals on lines 46 and 42 are applied to the authenticator 44, whose output signal 36 controls the switch 34 according to the following rule:

1. if the copyright flag detector 32 does not detect the copyright flag, the switch 34 is closed and the digital video signal at 31 goes to the lower stage.

2. If the copyright flag detector 32 detects the copyright flag, the switch 34 is turned on only when the authentication flag detector 40 also detects the authentication flag.

The authenticator 44 therefore only allows playback of the original copy protected digital cassette tape.

The digital video signal at 48 from switch 34 is applied to one input of a selection switch 50 and also to an input of an "a" descrambler 52, the output of descrambler 52 being applied to the other input of switch 50.

The copy protected digital tape cartridge is produced using algorithm a for scrambling, as will be described below, so switch 50 is configured to select the output of "a" descrambler 52 when copyright flag detector 32 generates a logic high level 46 (illustrated as a copy protected program). Otherwise switch 50 selects through digital video signal 48.

The "a" descrambler 52 uses the copyright flag output 51 of the copyright flag detector as a descrambling control signal. Thus, if there is no copyright indicia within the digital signal 31, no descrambling occurs or is required. The digital video output signal 56 from switch 50 is applied to one input of a selection switch 66 and to an input of a "B" scrambler 70, with the output of scrambler 70 being applied to the other input of switch 66.

The copy protected descrambled digital video signal from the compliant source is scrambled by algorithm "B". Switch 66 is thus configured to select the output of "B" scrambler 70 when copyright mark detector 32 detects a copyright mark. The output of the selector switch 66 is the final digital video output signal 68 of the digital VCR.

The clear or descrambled digital video signal 56 is also applied to a digital to analog converter 60, the output of the digital to analog converter 60 being applied to a color encoder 62 to produce an NTSC or PAL video signal output for an analog output line 64.

The logic high level 46 indicating the presence of the copyright flag also turns on an analog anti-copy (ACP) signal generator 58, which generator 58 is coupled to an encoder 62, so that the analog output of the digital VCR is copy protected when the copy protected cassette tape is played.

It is clearly important that the copy prevention system should not be destroyed by someone skilled in the art by turning on the VCR with some modification. Circuit integration and signal distribution decisions must be taken into account.

Fig. 2 is a simplified block diagram of a legitimate digital video disc player illustrating how the copy protection function can be implemented, noting that portion 100 within the dashed lines of the present block diagram is substantially the same as the corresponding portion of fig. 1. The only difference is that the control or guide track decoder 38 of fig. 1 is replaced by the radial servo error signal decoder of fig. 2.

The authentication subsystem, consisting of blocks 72, 40, 44 and 34 of fig. 2, extends the above-described technique to prevent such unforeseen events that would enable a CD recorder (CDR) that would be present to make a perfect copy of a pre-recorded disc. However, digital video discs may be provided with certified marks, as described in Ryan's acceptance application 08/267635 (filed 6/29 1994) for writing laser heads marked with radial modulation peak-to-peak of tens of nanometers. This radial modulation does not affect the program information recorded on the disc and is therefore not transferred to any replica made by the CDR. The absence of such radial modulation on a disc bearing a copyright mark will therefore indicate that the disc is an illegal copy and cause switch 34 to be opened to inhibit playback. The digital video disc system may also use the modulation scheme of the digital video system for digital video tape media described above.

The purpose and operation of the remaining parts of fig. 2 are exactly the same as the corresponding parts of fig. 1.

Fig. 3 is a simplified block diagram of a legitimate digital PPV demodulator, illustrating how the copy prevention function may be implemented. Note that this block diagram is similar to fig. 2, except that authentication subsystem blocks 72, 40, 44, and 34 of fig. 2 are not required, as there is no physical medium to authenticate. The purpose and operation of the remaining parts of fig. 3 is exactly the same as the corresponding parts of fig. 1 and 2.

Fig. 4 is a block diagram of a legitimate television set having a digital video input signal.

The digital video input signal 78 is applied directly to one input of the selection switch 86 and simultaneously to an input of the "B" descrambler 80, while an output 96 of the descrambler 80 is applied to another input of the switch 86.

The copyright flag detector 82 is also fed by the digital video signal 78 and its logic level output 84 controls the switch 86 so that the switch 86 selects the digital video signal 78 in the absence of a copyright flag and selects the descrambled signal 96 from the "B" descrambler 80 when a copyright flag is detected. The "B" descrambler utilizes the copyright flag as a descrambling control signal. So if no copyright indicia is present in the digital video signal 78, no descrambling occurs. Thus in any case the output of switch 86 on line 96 is a clear or descrambled video signal which can be displayed by the television set and which is coupled to one input of display selection switch 90.

An analog video signal 98 is input from the line to the television and to the other input of the switch 90. The output 92 of the switch 90 is applied to display electronics and controls 94. The display electronics and controls 94 employ conventional techniques and need not be discussed further to understand the present invention.

It is helpful to discuss the playback capabilities of copy protected and non-copy protected material.

If a user attempts to play an original, non-copy protected cassette tape, the tape is allowed to play normally since the copyright indicia is not detected. Similarly, if a user attempts to play a master copy protected cassette tape, the tape is allowed to play normally because both copyright and authentication indicia are detectable.

If a user attempts to play a copy of a non-copy protected program (regardless of the medium from which it originated), the cassette tape is allowed to play normally since the copyright indicia is not detected.

If a user attempts to play an illegal copy of a copy protected program, regardless of the medium from which it originated, the copyright notice is detected because it is passed on to all copies, whether they are a copy of a later generation or whether the copy engine is legitimate or not. However, the authentication mark is not passed on to the replica. The decision circuit in the VCR then does not allow the reproduction of this copy.

The copy protection method and apparatus described herein are effective even if a VCR manufacturer produces an illegal digital VCR. The owners of illegal VCRs can only play illegal copies of copy protected programs for their own use. Such copies cannot be played on any legitimate digital VCR, which may be the majority. Non-old and non-old image shop staff and other image pirates cannot use these illegal VCRs for illegal copying, because illegal copies can only be played on illegal VCRs, and pirates have to publicize their products to be played on only a small number of illegal VCRs, thereby drawing attention and risking piracy.

Illegal VCRs are not able to play master copy protected cassette tapes because the absence of an "a" descrambler in an illegal VCR would prohibit it from descrambling the copy protected tape, which would greatly limit the market for such machines.

It is not feasible to remove copyright notice with a "black box" to break the copy protection. The lack of copyright notice makes it impossible for a television to descramble and display the digital video image.

The above description is exemplary rather than limited to these. Further modifications will be apparent to persons skilled in the art in light of this description of the invention. It should be appreciated that while no consumer digital video recording device is currently available, professional systems for digital video are available and the above-described apparatus and method can be readily adapted to such currently commercialized digital video recorders.

TABLE 1

Playback of videoOriginal editionPrerecorded digital cassette tape

	Playback VCR
					Legal digital VCR		Illegal digital VCR
	Cassette type	Analog output	Digital output	Analog output					Digital output
Coded					The copy-protected output can be viewed on all conventional television sets	Copy protected output for viewing on future television sets with digital input	Scrambled, unviewable output	Scrambled, unviewable output
	Uncoded	Unprotected output can be watched on all conventional televisions	Unprotected output for viewing on future television with digital input	Unprotected output can be watched on all conventional televisions					Unprotected output for viewing on future television with digital input

TABLE 2

Playback of a replica of encoded digital video

		Playback VCR
						Legal digital VCR		Illegal digital VCR
		Digital video source	Duplicating machine	Analog output	Digital output					Analog output	Digital output
Legal digital VCR and digital video disc player	Legal digital VCR					No output (blank copy)	No output (blank copy)	No output (blank copy)	No output (blank copy)
		Illegal digital VCR	Without output	Without output	Scrambled, unviewable output					Copy protected output for viewing on future television sets with digital input
	Illegal digital VCR and digital video disc player					Legal digital VCR	No output (blank copy)	No output (blank copy)	No output (blank copy)		No output (blank copy)
Illegal digital VCR		Without output	Without output	Scrambled, unviewable output	Scrambled, unviewable output

TABLE 2

Playback of videoEncodingOf digital videoReproduction

		Playback VCR
						Legal digital VCR		Illegal digital VCR
		Digital video source	Duplicating machine	Analog output	Digital output					Analog output	Digital output
Legal digital VCR and digital video disc player	Legal digital VCR					No output (blank copy)	No output (blank copy)	No output (blank copy)	No output (blank copy)
		Illegal digital VCR	Without output	Without output	Scrambled, unviewable output					Copy protected output for viewing on future television sets with digital input
	Illegal digital VCR and digital video disc player					Legal digital VCR	No output (blank copy)	No output (blank copy)	No output (blank copy)		No output (blank copy)
Illegal digital VCR		Without output	Without output	Scrambled, unviewable output	Scrambled, unviewable output

TABLE 3

Playback and recordingCopy protection ⁽¹⁾VHS of 8 mm orAnalog video ⁽²⁾Duplication of a source

	Playback VCR
					Legal digital VCR		Illegal digital VCR
	Duplicating machine	Analog output	Digital output	Analog output					Digital output
Legal digital VCR					No output (blank copy)	No output (blank copy)	No output (blank copy)	No output (blank copy)
	Illegal digital VCR	Unprotected output can be watched on all conventional televisions	Unprotected output for viewing on future television with digital input	Unprotected output can be watched on all conventional televisions					Unprotected output for viewing on future television with digital input

(1) Protected by Macrovision's standard cassette anti-copy process

(2) Protected by Macrovision standard PPV anti-copy processing at analog output port of decoder in digital machine

Claims (43)

1. An apparatus for playing back material digitally recorded on a recording medium, comprising:

a mechanism for playing the recording medium;

a digital output port operatively coupled to the mechanism to provide a digital data signal from the mechanism;

a first detector for detecting an authentication signal in the digital data signal;

a second detector for detecting a copyright flag signal in the digital data signal;

wherein the copyright notice signal and the authentication signal, if present, are both coupled to an authenticator;

when the authentication signal and the copyright flag signal are both coupled to the authenticator, the authenticator couples a command to activate the first switch;

the activation of the first switch couples the digital data signal to a first input of a second switch and to a descrambler;

the descrambled output of the descrambler is coupled to a second input of the second switch;

the copyright flag signal is further coupled to a control element of the second switch to couple the output of the descrambler to a digital-to-analog converter, a first input of a third switch, and a scrambler;

an output of the scrambler is coupled to a second input of the third switch;

the output of the third switch provides a scrambled output when the copyright flag signal is present and provides a clear digital data signal when the copyright flag signal is absent;

the copyright mark signal starts an analog anti-copy generator;

the digital-to-analog converter is operatively coupled to an output of the second switch, the output of the second switch containing clear digital data when the copyright flag signal is not present on the control element of the second switch, and the output of the second switch containing descrambled digital data when the copyright flag signal is present on the control element of the second switch;

the digital-to-analog converter converts the digital data signal into an analog signal;

the anti-copy generator generates an analog anti-copy signal for correcting the analog signal generated by the digital-to-analog converter; and

wherein the modified analog signal is encoded into a copy protected analog signal.

2. The apparatus of claim 1, wherein the digital data signal and the analog signal are video signals.

3. The apparatus of claim 1, wherein the copyright flag signal includes at least one bit of data at a predetermined location within the digital signal.

4. The apparatus of claim 2, wherein said generated copy protection signal comprises pulse pairs inserted in at least some blanking intervals of said analog video signal, each pulse pair comprising a positive going pulse and a negative going pulse.

5. The apparatus of claim 1, wherein the recording medium is a magnetic tape.

6. The apparatus of claim 1, wherein the recording medium is an optical disc.

7. The apparatus of claim 2, wherein the generated copy protection signal includes pulses added to a blanking interval of the analog video signal.

8. The apparatus of claim 2, wherein the generated copy protection signal includes variations in the duration of horizontal intervals within the analog video signal.

9. The apparatus of claim 2, wherein the generated copy protection signal includes a change in a number of horizontal line intervals in a video frame of the analog video signal.

10. The apparatus of claim 2, wherein the copy protection signal includes at least 1 bit of data in each field of the video signal.

11. The apparatus of claim 1, wherein the authentication signal comprises: frequency modulation of the digital data signal.

12. The apparatus of claim 11, wherein the frequency modulation comprises: a square wave having a frequency such that an integral multiple of a complete track is recorded in each period of the square wave.

13. The apparatus of claim 1, wherein the mechanism is also a recording mechanism, and further comprising:

a digital input port receiving a digital input signal from an external source;

means for recording the digital input signal on the recording medium and applying the digital input signal to the mechanism;

a third signal detector for detecting copy protection information present in the digital input signal; and

means for inhibiting recording based on detecting the presence of copy protection information in the digital input signal.

14. The apparatus of claim 13, wherein the digital input signal is a video signal.

15. The apparatus of claim 13, further comprising a tuner for extracting the digital input signal from a modulated radio frequency signal.

16. The apparatus of claim 13, further comprising:

an analog input port receiving an analog input signal;

an analog-to-digital converter for converting the analog input signal into a converted digital signal;

means for providing the converted digital signal to the mechanism; and

an analog signal detector for detecting an analog copy protection signal present in the analog input signal and disabling recording of the analog input signal accordingly.

17. The apparatus of claim 16, wherein said means for providing said converted digital signal to said mechanism is included in a fourth switch that receives said digital input signal and said converted digital signal and provides one or the other to said mechanism based on the coupling established by said switch.

18. The apparatus of claim 16, wherein the analog signal detector includes an automatic gain control circuit responsive to the analog copy protection signal.

19. The apparatus of claim 16, wherein the analog signal detector includes circuitry responsive to the analog copy protection signal.

20. The apparatus of claim 16, wherein the analog signal detector includes means for detecting the analog copy protection signal and generating a record inhibit signal based thereon.

21. The apparatus of claim 13, wherein the second signal detector detects at least one bit of data at a predetermined location in the digital input signal.

22. A method of inhibiting copying of material digitally recorded on a recording medium, the material including copy protection information, the method comprising the steps of:

playing the data from the recording medium;

providing a digital data signal from the medium;

detecting an authentication signal within the digital data signal;

detecting the copy protection information as a copyright signature signal including any scrambling of the played material;

processing the digital data signal when both the authentication signal and the copyright flag signal are present;

descrambling the copy protected digital data signal;

converting the playing data from the digital data signal to an analog signal;

generating an analog anti-copy signal according to the detected anti-copy information;

modifying the analog signal with the generated analog copy protection signal;

outputting the copy-protected analog signal;

adding a new anti-copy signal to the descrambled signal and re-scrambling the descrambled digital signal; and

the re-scrambled digital signal containing the new copyright flag signal is output.

23. The method of claim 22, wherein the digital signal and the analog signal are video signals.

24. The method of claim 23, wherein the copy protection information is at least one bit of data at a predetermined location within the digital signal.

25. The method of claim 23, wherein the copy protection information comprises a scrambled portion of the video signal.

26. The method of claim 23, wherein the authentication signal comprises: frequency modulation of the digital signal.

27. The method of claim 26, wherein the frequency modulation of the authentication signal comprises: the modulated signal is modulated with a square wave having a frequency such that an integral multiple of a complete track is recorded in each period of the square wave.

28. The method of claim 23, wherein the generated signal comprises pulse pairs inserted in at least some blanking intervals of the analog video signal, each pulse pair comprising a positive-going pulse and a negative-going pulse.

29. The method of claim 22, wherein the recording medium is a magnetic tape.

30. The method of claim 22, wherein the recording medium is an optical disc.

31. The method of claim 23, wherein the generated analog anti-copy signal includes variations in duration of horizontal intervals within the analog video signal.

32. The method of claim 23, wherein the generated analog anti-copy signal includes a change in a number of horizontal line intervals per video frame.

33. The method of claim 24, wherein the one bit of data is in each field of the digital video signal.

34. The method of claim 22 wherein the material is also recorded and further comprising:

receiving a digital input signal from an external source;

providing a digital input signal for recording the digital input signal on the recording medium;

detecting copy protection information present in the digital input signal; and

means for inhibiting recording in response to detecting the presence of the copy protection information in the digital input signal.

35. The method of claim 34, wherein the digital input signal is a video signal.

36. The method of claim 34, further comprising extracting the digital input signal from a radio frequency signal.

37. The method of claim 34, further comprising:

receiving an analog input signal;

converting the analog input signal into a converted digital signal;

detecting an analog copy protection signal present in the analog input signal and inhibiting recording of the analog input signal in response thereto; and

the converted digital signal is coupled to a recording mechanism in the absence of a copy protection signal.

38. The method of claim 34, further comprising:

providing a switch for receiving the digital input signal and the converted digital signal; and

one or the other signal is recorded according to the connection established by the switch.

39. The method of claim 35, wherein the detecting of the analog signal includes providing an automatic gain control circuit that is directly responsive to the analog copy protection signal.

40. The method of claim 37, wherein the detecting of the analog signal includes providing a circuit that is directly responsive to the analog copy protection signal.

41. The method of claim 37, wherein the detecting of the analog signal comprises:

detecting the analog anti-copy signal; and

a recording inhibit signal is generated accordingly.

42. A method of viewing copy protected video material containing a copy protection mark signal and an authentication mark signal, comprising the steps of:

detecting a first copyright protection flag signal in the video data;

detecting an authentication signal in the video data;

descrambling the scrambled part using the copyright protection signal as a control element upon detection of the copyright flag signal and the authentication signal;

adding a second copyright protection mark signal and re-scrambling the descrambled video data;

outputting the re-scrambled signal to a viewing device;

detecting the second copy right mark signal in the viewing device;

descrambling the re-scrambled signal using the second copyright flag signal; and viewing the descrambled re-scrambled video signal.

43. An apparatus for receiving a copy protected video signal having a copyright flag signal and a scrambled portion, comprising:

means for receiving the video signal;

the apparatus includes a tuner for demodulating the video signal;

a copyright indicia detector operatively coupled to the tuner, a first input of the first selector, and an input of the descrambler;

when the first copyright token signal exists in the video signal, the descrambler descrambles the video signal and outputs the descrambled video signal to a second input of the first selector;

when the first copyright flag signal is detected, the copyright flag detector outputs a control signal to a control element of the first selector, the first selector couples the descrambled video signal to the digital-to-analog converter, a first input of a second selector, and the scrambler;

the scrambler re-scrambles the descrambled video signal and adds a second copyright mark signal;

an output of the scrambler is coupled to a second input of the second selector, wherein the second selector outputs the output of the scrambler when the first copyright token signal is present and the second selector selects the input of the scrambler when the first copyright token signal is not present;

wherein the output of the second selector provides a digital output for the device;

the control signal is coupled to an analog anti-copy signal generator to generate one or more analog anti-copy signals when the first copyright token signal is present;

an output of the digital-to-analog converter is coupled to an analog encoder to produce an analog output signal; and

the one or more analog copy protection signals are coupled to the digital-to-analog converter and the encoder to produce an analog output signal having an analog copy protection component.